Last night I was out on my 94 m900,about mid ride i was accelerating away from a stop sign and it started running very rough like it was intermittently firing on both cyclinders, I limped home,just barely had enough power to make it up hill that i live on. Bike idles fine and seems to throttle normal if you pull choke knob,but after you push choke knob in it goes back to running rough.Bike has been really well taken care of but previous owner did mix race fuel in with pump gas,Ive owned bike for less than a week and did top off fuel with premium 60 miles ago.Not sure wich direction to take troubleshooting,really bummed im already having issues.Really appreciate any advice or help..thanks
Could be a lot of things. Is the engine modded?
Has the bike been in the rain lately or sat for more than a couple of weeks with the fuel that's in the tank now?
It could be water in the fuel or phase separation of the ethanol fuel which amounts to the same thing as water.
It could also be a dirty fuel filter.
I'd start with fuel as it's easy and a pretty common issue these days.
as far as I know and have been told bike is not modded,,bike ran great before this.fuel is less than a week old.where is fuel filter located,im assuming under the tank...or is it in carbs themselves?
There is a filter under the tank. There are also screens in the fuel inlets in the carbs. My first step would be to drain the fuel from the float bowls into a clear clean container and inspect for contamination. There are two black plastic tubes by the rear of the engine on the right side. If you follow them up to the carbs you will see the the crews that allow you to drain the floats, 8mm heads if I remember. If gray sludge comes out your bike is suffering alcohol poisoning.
I had exactly the same symptoms with a clagged fuel filter. I also used the choke to give the motor enough fuel to limp home at low revs. It's true that bad fuel and clagged plugs can give similar symptoms. Fresh fuel, the auto style external fuel filter and a set of plugs are cheap fixes.
Down here in OZ we are beginning to get the alcohol related issues in fuel.
The other alcohol issues we have had for ages.. :D
Cheers [drink]
Where do you live and how humid & cold is it there now?
Have you lifted tank, is fuel line in the free?
Quote from: koko64 on October 21, 2010, 03:39:19 PM
I had exactly the same symptoms with a clagged fuel filter. I also used the choke to give the motor enough fuel to limp home at low revs. It's true that bad fuel and clagged plugs can give similar symptoms. Fresh fuel, the auto style external fuel filter and a set of plugs are cheap fixes.
Down here in OZ we are beginning to get the alcohol related issues in fuel.
The other alcohol issues we have had for ages.. :D
Cheers [drink]
The other alcohol issues have always been universal. [beer]
Quote from: humorless dp on October 21, 2010, 04:25:40 PM
The other alcohol issues have always been universal. [beer]
Cheers [beer]
[beer]
Watch it, dp, ypu might be developing a sense of humor....
Quote from: greenmonster on October 21, 2010, 05:13:40 PM
[beer]
Watch it, dp, ypu might be developing a sense of humor....
Not a chance Gert. ;)
Thanks guys,drained gas and removed filter,grabbing a new filter n plugs today and fresh gas,when i drained fuel from filter there was a ton of mung that came out so keeping my fingers crossed that thats what was wrong.Good starting point,guess ill yank carbs next,its about time to put bikes away for winter anyway...